Firewall Screens 10-3Contivity 221 VPN Switch User’s Guide2. Is it possible to modify the rule to be more specific? For example, if IRC is blocked for allusers, will a rule that blocks just certain users be more effective?3. Does a rule that allows Internet users access to resources on the LAN create a securityvulnerability? For example, if FTP ports (TCP 20, 21) are allowed from the Internet to theLAN, Internet users may be able to connect to computers with running FTP servers.4. Does this rule conflict with any existing rules?Once these questions have been answered, adding rules is simply a matter of plugging theinformation into the correct fields in the WebGUI screens.10.3.3 Key Fields For Configuring RulesActionShould the action be to Block or Forward?“Block” means the firewall silently discards the packet.ServiceSelect the service from the Service scrolling list box. If the service is not listed, it is necessary tofirst define it. See section 10.7 for more information on predefined services.Source AddressWhat is the connection’s source address; is it on the LAN or WAN? Is it a single IP, a range of IPsor a subnet?Destination AddressWhat is the connection’s destination address; is it on the LAN or WAN? Is it a single IP, a range ofIPs or a subnet?10.4 Connection Direction ExamplesThis section describes examples for firewall rules for connections going from LAN to WAN andfrom WAN to LAN.LAN to LAN/Contivity 221, WAN and WAN/Contivity 221 rules apply to packets coming in onthe associated interface (LAN or WAN respectively). LAN to LAN/Contivity 221 means policiesfor LAN-to-Contivity 221 (the policies for managing the Contivity 221 through the LAN interface)and policies for LAN-to-LAN (the policies that control routing between two subnets on the LAN).Similarly, WAN to WAN/Contivity 221 polices apply in the same way to the WAN ports.
